1. Field of the Invention
The present invention relates to a shift register of a liquid crystal display (LCD) device, and more particularly, to a shift register which can prevent malfunctioning of device by decreasing load on a discharging voltage source line and can decrease a size of stage.
2. Discussion of the Related Art
In general, a liquid crystal display (LCD) device displays images by controlling light transmittance of liquid crystal with the use of an electric field applied. For this, the LCD device is provided with a liquid crystal panel including a plurality of pixel regions arranged in a matrix configuration, and a driving circuit for driving the liquid crystal panel.
The liquid crystal panel comprises a plurality of gate lines and a plurality of data lines, wherein each gate line is formed orthogonal to each data line, to thereby define a plurality of pixel regions. In addition, the liquid crystal panel includes pixel electrodes and a common electrode to apply the electric field to the pixel regions, respectively. At this time, the gate lines are driven in response to a scan pulse generated from a shift register, in sequence.
FIG. 1 is a diagram illustrating one stage in a related art shift register. As shown in FIG. 1, the related art shift register includes a plurality of stages 100. The stages 100 are cascaded. Each stage is supplied with a clock pulse from a clock transmission line, and outputs the scan pulse in sequence. Each stage includes a plurality of nodes; a node controller to control a signal state of the node; and an output unit, connected to the node, to output the scan pulse in response to the signal state of the node. In order to maintain the node as a discharging state, the related art shift register uses a discharging voltage source corresponding to a constant voltage.
However, the related art shift register has the following disadvantages.
When the discharging voltage source is supplied to the node controller and output unit included in each stage, there is large load on a discharging voltage source line for transmitting the discharging voltage source. The related art shift register has may malfunction since the node included in each stage is not discharged properly.
Also, the related art stage is provided with at least two nodes and a plurality of switching devices to control the nodes, so that the shift register is increased in size. This large size of shift register may cause the limitation on technology of forming the shift register in the liquid crystal panel.